Several viruses produce latent infection in humans and can reactivate to produce recrudescent or persistent disease. One such disease is the human immunodeficiency virus (HIV). HIV is associated with a progressive catastrophic disease in certain primates, including humans. Humans infected with HIV experience proliferation of a certain class of white blood cells known as cytotoxic T-lymphocytes (CTL). The final stage of this disease is commonly known as acquired immune deficiency syndrome (AIDS).
It is well known in the art that the clinical signs and symptoms of AIDS are primarily due to a profound loss of all lymphocytes marked with the CD3 and CD4 antigens (CD4+ T-lymphocytes). It is also generally accepted that the infectious agent in AIDS is the human immunodeficiency virus (HIV). Although HIV infects and destroys CD4+ cells, the number of cells infected is inadequate to account for the profound and indiscriminate loss of these cells that occurs in individuals infected with HIV. It has been suggested by those in the field that autoimmunity may play a role in the pathogenesis of AIDS. However, few have suspected a pathogenic cytotoxic T-lymphocyte (CTL).
Rather, it is generally accepted by those skilled in the art that CTL's are beneficial for those infected with HIV since it is believed CTL's help control the infection, i.e., CTL's are believed to be prognosticators that delay the progression of AIDS. Kilmas, et al, "Phase I Trial of Adoptive Therapy with Purified CD8 Cells in HIV Infection", Int. Conf. AIDS, July 19-24, 1992; Abstract No. POB 3446, for example, have described infusion of CTL's into the bloodstream of HIV-infected patients as an experimental method of treatment. This particular type of infusion was directed to the mitogen-expanded colonies of the host patient's autologous CD8+ cells, a lymphocyte population that includes CTL's.
However, Zarling, et al, "HIV-Infected Humans, But Not Chimpanzees, Have Circulating Cytotoxic T-Lymphocytes That Lyse Uninfected CD4+ Cells", J. Immunol. 1990; 144: 2992-98 have shown that HIV-infected humans have an anti-self, anti-CD4 CTL in their circulating blood that lyses healthy, uninfected CD4+ cells. No such CTL was found in the blood of HIV-seronegative humans. Moreover, no such CTL or suicide cell was found in the blood of HIV-infected chimpanzees. This is significant because HIV infection manifests as a nonpathogenic colonization in the blood and tissue of chimpanzees.